Elucidating Pattern Formation in Anabaena: A Genetic Approach

阐明鱼腥藻模式的形成：遗传方法

• 批准号: 8702368
• 负责人: Coleman Wolk
• 金额: $ 23.93万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-11-01 至 1991-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8702368&HistoricalAwards=false
• 关键词: Elucidating; Pattern; Formation; Anabaena; Genetic

Anabaena in a filamentous cyanobacterium that responds to nitrogen deprivation by elaborating along the filament semi-regularly spaced cells (heterocysts) specialized for N2-fixation. The pattern of heterocysts is initiated amd maintained by an inhibitory field emanating from developing and mature heterocysts. Dr. Wolk has isolated mutants that are defective early in development and have found cosmids that complement certain of these mutants. To study spatial aspects of gene expression in the developing filament, he has developed a vector that facilitates transcriptional fusions to luciferase (lux) and their maintenance in Anabaena. He proposes to: 1. Further develop and characterize the use of lux to monitor gene expression from individual cells. 2. Identify a gene that is expressed early in development, specifically in cells fated to become heterocysts. Candidate promoters will be fused to lux and light emission along the filament monitored through the course of development. 3. Subject Anabaena carrying the successful promoter/lux fusions to transposon mutagenesis and antisense RNA phenotypic mutagenesis to search for genes that regulate the expression of the promoter. Such genes will be identified by altered light emission. Dr. Wolk will focus on mutants that respond to N- stepdown by inducing light emission in all cells rather than only in developing heterocysts. 4. Clone genes that affect the expression of the promoter and, by fusing them to lux, localize their expression in time and space. Higher eukaryotes develop from single cells to collections of cells of varied types and functions, but inhomogeneous differentiation in prokaryotes is rare. Dr. Wolk proposes to exploit the differentiation of the filamentous cyanobacterium, Anabaena, to study these processes in a simple prokaryote where powerful genetic techniques can be utilized.

丝状蓝藻中的鱼腥藻通过沿着丝状半规则间隔的专门用于固氮的细胞（异形细胞）来响应氮缺乏。 异形胞的模式是由发育和成熟的异形胞发出的抑制场启动和维持的。 沃尔克博士分离出了在发育早期就有缺陷的突变体，并发现了可以补充其中某些突变体的粘粒。 为了研究发育丝中基因表达的空间方面，他开发了一种载体，可促进与荧光素酶 (lux) 的转录融合及其在鱼腥藻中的维持。 他建议： 1. 进一步开发和表征使用 lux 来监测单个细胞的基因表达。 2. 鉴定在发育早期表达的基因，特别是在注定成为异形细胞的细胞中表达的基因。 候选启动子将与开发过程中监测的灯丝沿线的勒克斯和光发​​射融合。 3.携带成功的启动子/lux融合体的鱼腥藻对象进行转座子诱变和反义RNA表型诱变，以寻找调节启动子表达的基因。 这些基因将通过改变光发射来识别。 Wolk 博士将重点关注通过在所有细胞中诱导光发射而对 N-降压做出反应的突变体，而不仅仅是在发育中的异形细胞中。 4. 克隆影响启动子表达的基因，并通过将它们与lux融合，在时间和空间上定位它们的表达。 高等真核生物从单个细胞发展为不同类型和功能的细胞集合，但原核生物中的不均匀分化很少见。 Wolk 博士建议利用丝状蓝细菌 Anabaena 的分化，在简单的原核生物中研究这些过程，其中可以利用强大的遗传技术。